Vent for liquid circuit breaker

ABSTRACT

A liquid circuit breaker is equipped with an exhaust vent that has a part which is provided with a tapped bore for receiving a screw. The bore and screw form a helical passage for directing gas away from the circuit breaker while at the same time preventing discharge of the liquid.

I United States Patent 1 11 3,560,634

[72] Inventors Furdoon Battiwala; [50] Field of Search 200/ 1 50.2, Gunther Sinnecker; Stephan Boerger; Gerd l50AN; 337/250. 249, 204 Pawlak, Berlin, Germany [21 1 APPL No 737,150 [56] References Cited [22] Filed June 14, 1968 UNITED STATES PATENTS 1 Patented 1 1971. 1,192,397 7/1916 Downes et a1. 200/ 1 50 1 1 Asslgnees 518mm Akflengesellscha 1,700,080 1 1929 Sandin 337 250 Berlin and Munich, Germany [32] Priority June 15, 1967 Primary ExammerR0bert S. Macon [33] Germany Attorneys-Curt M. Avery, Arthur E. Wilfond, Herbert L. S1 Lerner and Daniel J. Tick [54] b P il BREAKER ABSTRACT: A liquid circuit breaker is equipped with an exalms rawmg haust vent that has a part which is provided with a tapped bore [52] US. Cl 200/ 150, for receiving 'a screw. The bore and screw form a helical 337/204, 337/250 passage for directing gas away from the circuit breaker while [5 l Int. Cl.. Htllh 33/68 at the same time preventing discharge of the liquid.

PATENTEI] FEB 2192: 3,550 5 4 [we/750m:

VENT FOR LIQUID CIRCUIT BREAKER Our invention relates to liquid circuit breakers and more particularly to vents provided with such breakers for directing gases from the breaker.

in a liquid circuit breaker, gases are produced by the circuit-breaking arc and must be withdrawn from the breaker. Vents used for this purpose have been equipped with devices which prevent the discharge of the liquid. One such device is described in German Pat. No. 573,181, and utilizes a slider for closing the vent opening when the gases in the breaker develop a high pressure. However, the required mobility of the slider renders it complicated and expensive. In addition, the vent opening is throttled the most at the same time that the greatest amount of gas must be removed.

It is an object of our invention to provide a vent that does not require moving parts and which is simple to produce.

It is another object of our invention to provide a vent that directs gases away in the absence of any danger that the quenching liquid will escape.

In accordance with a feature of our invention a spiral groove is formed between the inner surface of a tapped bore and the outer surface of a screw seated in the bore. The relatively narrow winding groove prevents droplets of liquid from being carried along even at high flow velocities.

In a preferred embodiment of the invention, the tapped bore extends through a threaded plug which is seated in the housing of a liquid circuit breaker. For this purpose, the material selected for the plug should be harder or be otherwise of a higher quality than the material selected for the circuit breaker housing. This selection will produce an especially precise tapped bore at low cost. In addition, the bore provided in the breaker housing for the plug may also be used as a filler opening for the quenching liquid.

In cross section, the plug can exhibit a funnel-shaped extension. This extension ensures that small amounts of liquid, escaping in the form of vapor with the gases, will be collected after condensing without any danger of contaminating the circuit breaker.

A wire screen may be placed at the end of the tapped bore facing the circuit breaker interior for the purpose of preventing foreign particles such as, for example, enamel beads from becoming lodged in front of the groove. A simple assembly is afforded by securing the wire screen with an annular disc fastened by calking.

A contamination of the groove from the outside can be prevented by a cap which extends over the tapped bore, the cap being fastened with the screw. In this connection, it is expedient to place a spacer tube between the cap and the tapped bore in surrounding relation to the screw. The required crosssectional area of the opening through which the gases pass from the groove is provided by a toothed disc placed intermediate the spacer tube and the adjacent surface at the edge of the tapped bore.

The invention will be further elucidated with reference to the embodiment illustrated by way of example on the accompanying drawings in which:

FIG. I is a schematic diagram of a liquid circuit breaker equipped with a device according to the present invention.

FIG. 2 is a schematic view, in section, showing an embodiment of the vent of the present invention.

Referring first to FIG. 1, a 10 kilovolt liquid circuit breaker I is shown in its entirety. The housing 2 has anoperating mechanism which is not illustrated. The pole column 4 is mounted on the housing 2 by means of the support insulators 3. The pole column 4 is comprised of a metallic gear housing 5 carrying live voltage, an oil-filled moulded plastic chamber 6 and a circuit breaker had 7 made of cast aluminum. For the gases, the upper end of head 7 is provided with a vent 8, the latter being a device according to the present invention.

As shown in FIG. 2, the device features a plug I0 threadably seated in a tapped bore 11 of the circuit breaker head 7. The plug is produced from hexagonal steel and has a cross section in the shape of a funnel. The plug 10 exhibits this funnel shape because of the cavity 13 provided above the tapped bore 12.

The tapped bore 12 has a metric thread. However, the inner diameter of this thread is increased because the bore, in which the thread is cut and which determines this diameter, was not drilled to a 4 7/10 millimeter diameter. The bore was instead drilled to a diameter of 5 5/10 millimeters, the latter being increased above the 4 7/l0 by approximately l7 percent. The screw 14 has a standard thread profile and is driven into the tapped bore I2. A helical groove of triangular cross section is thereby formed between the inside of the tapped bore I2 and the outer surface of the screw I4. The groove functions as an exhaust passage and connects the circuit beaker interior with the atmosphere. In the illustrated embodiment, the passage was formed with a screw depth of about ten millimeters.

By means of a spring ring 16, the screw I4 presses a spacer tube 17 made of hexagonal steel against the conical bottom surface 18 of cavity 13. The surface 18 forms a margin in the region of the tapped bore 12. A toothed disc I9 is placed intermediate the margin and the spacer I7, and functions to break up rising bubbles of quenching liquid in the event that such bubbles develop. A cap 20 is provided at the other end of spacer 17 for covering the tapped bore 12 so that only a narrow circular opening 21 remains through which virtually no contaminates can enter.

The lower end of the tapped bore 12 facing the interior of the circuit breaker is covered with a wire screen 24. The screen 24 is inserted into a recess of the plug 10 and held in place by an annular disc 25, the latter being secured by calking the edge 26.

According to the invention, the size of the groove can be adjusted to accommodate a given set of requirements having the same length, this denotes that the penetrability of the groove is increased if the difference between the thread profile of the tapped bore and the thread profile of the screw is increased. In this regard, it has generally been found advantages to provide a larger groove cross section than that afforded by the normal tolerance in winding dimensions. This can be achieved by flattening one or both thread profiles.

Preferably, the inner diameter of the thread in the tapped bore is increased by approximately I0 to 20 percent. This means that the diameter of the drill need to cut the thread is, for example, nine-tenths of the outer thread diameter instead of normal eight-tenths. The same result can also be obtained by making the outer thread diameter of the screw smaller. If required, a larger outlet cross section can be obtained by positioning several devices of the invention on a circuit breaker. Virtually no additional expense is incurred thereby because of the low cost of these devices.

In practicing the invention, most any winding is suitable, the optimum dimension of a particular requirement being determined by a few tests. Metric threads were used in the tests of the invention.

The vent developed in accordance with the invention is simple to produce and has exhibited excellent results in numerous tests conducted with intermediate voltage circuit breakers. The embodiment of the vent of the invention depicted in FIG. 2 provides the advantageous facility of permitting the circuit breaker to be replenished with quenching liquid. For this purpose, the plug 10 which is provided with a hexagonal form is unscrewed from the tapped bore 1 I and thereby makes a large opening available. A sealing ring 27 may be used to seal the tapped bore 11.

To those skilled in the art it will be obvious upon a study of this disclosure that our invention permits of various modifications with structural features and hence that the invention may be given embodiments other than particularly illustrated and described herein, without departing from the essential features of the invention and within the scope of the claims annexed hereto.

We claim:

1. In a liquid circuit breaker having a chamber containing quenching liquid, said chamber having a head portion, a vent for exhausting gas volatilized from the quenching liquid in the chamber, said vent comprising a sleeve member comprising a plug inserted in the head portion of the chamber of said circuit breaker and having a bore through said plug communicating at one end thereof with he chamber of the liquid circuit breaker, said bore having an internal thread, and a screw threaded with clearance in said bore of said sleeve member so that the inner surface of the sleeve member and the outer surface of the screw define helical passage means for exhausting from the chamber gas volatilized from the liquid in the chamber while substantially preventing discharge of liquid 2. In a liquid circuit breaker according to claim 1, said internal thread having an inner diameter to percent greater than the inner diameter of said screw thread.

3. In a liquid circuit breaker according to claim 1, said plug having an extension, said extension defining a funnel shaped cavity extending longitudinally from said bore.

4. in a liquid circuit breaker according to claim 1, said vent including a wire screen covering said bore at the end thereof communicating with the chamber. I

5. in a liquid circuit breaker according to claim 4, said vent including an annular disc for holding said screen, and fastening means being situate on said disc for fastening the latter.

6. In a liquid circuit breaker according to claim 5, said fastening means being a calking material 7. in a liquid circuit breaker according to claim 1, said vent including a cover means overlying said bore and being fastened by said screw.

8. In a liquid circuit breaker according to claim 7, said vent including a spacer means surrounding said screw and being located intermediate said bore and said cover means.

9. In a liquid circuit breaker according to claim 8. said vent including a toothed disc means located intermediate said spacer means and said plug at said bore means.

10. In a liquid circuit breaker according to claim I. the liquid circuit breaker being provided with a plurality of said vents.

11. In a liquid circuit breaker according to claim 1. said plug having a screw thread so as to be removable by unscrewing. 

1. In a liquid circuit breaker having a chamber containing quenching liquid, said chamber having a head portion, a vent for exhausting gas volatilized from the quenching liquid in the chamber, said vent comprising a sleeve member comprising a plug inserted in the head portion of the chamber of said circuit breaker and having a bore through said plug communicating at one end thereof with he chamber of the liquid circuit breaker, said bore having an internal thread, and a screw threaded with clearance in said bore of said sleeve member so that the inner surface of the sleeve member and the outer surface of the screw define helical passage means for exhausting from the chamber gas volatilized from the liquid in the chamber while substantially preventing discharge of liquid
 2. In a liquid circuit breaker according to claim 1, said internal thread having an inner diameter 10 to 20 percent greater than the inner diameter of said screw thread.
 3. In a liquid circuit breaker according to claim 1, said plug having an extension, said extension defining a funnel shaped cavity extending longitudinally from said bore.
 4. In a liquid circuit breaker according to claim 1, said vent including a wire screen covering said bore at the end thereof communicating with the chamber.
 5. In a liquid circuit breaker according to claim 4, said vent including an annular disc for holding said screen, and fastening means being situate on said disc for fastening the latter.
 6. In a liquid circuit breaker according to claim 5, said fastening means being a calking material.
 7. In a liquid circuit breaker according to claim 1, said vent including a cover means overlying said bore and being fastened by said screw.
 8. In a liquid circuit breaker according to claim 7, said vent including a spacer means surrounding said screw and being located intermediate said bore and said cover means.
 9. In a liquid circuit breaker according to claim 8, said vent including a toothed disc means located intermediate said spacer means and said plug at said bore means.
 10. In a liquid circuit breaker according to claim 1, the liquid circuit breaker being provided with a plurality of said vents.
 11. In a liquid circuit breaker according to claim 1, said plug having a screw thread so as to be removable by unscrewing. 